The purpose of this research is to investigate the relative importance of Avicennia marina organic matter in the feeding of Ilisha melastoma fish in the Mangrove Biosphere Reserve,It was stable isotope approach. Three primary food sources including mangrove tree leaves, microphytobenthos and suspended organic particles were analyzed isotopically. The samples of primary food sources and fish are converted into pure and simple gases such as CO, CO2 and N2 after minimizing the size and turning into powder. Then the identified isotope ratios are compared with a measured standard and the exact amount of isotope formed in the sample is obtained. In this research, sampling was done seasonally in August in the summer season and February in the winter season of 2019 in the mangrove ecosystems of Bandar Khmer, Hormozgan province. In the summer season, the average stable carbon isotope of primary food sources fluctuated from-28. 07 units per thousand for mangrove leaves to-13. 58 units per thousand for microphytobenthos. This average in the winter season was obtained from-28. 05 units per thousand for mangrove leaves to-13. 54 units per thousand for microphytobenthos. The average stable nitrogen isotope of primary food sources in the summer season fluctuated from 1. 44 units per thousand for microphytobenthos to 10. 72 units per thousand for suspended organic particles. The results of this research showed that in the summer season, suspended organic particles with 63% and in the winter season, microphytobenthos with 45% play the most important role in providing the food needed by the small shemsk fish.

Harmful algal blooms caused by dinoflagellates have significant adverse effects on environmental and public health. This study aimed to investigate the effect of water physicochemical parameters on the annual cycle of epiphytic dinoflagellates in the northern Chabahar Bay coastal waters of the Oman Sea (Iran). The macroalgal samples with associated epiphytes were collected seasonally from 6 coastal sites in spring, summer, atumn 2019 and winter 2020. The water physicochemical parameters were measured, and the data were analyzed using a one-way ANOVA and the principal component analysis (PCA). Twelve potentially toxic dinoflagellate species from five genera were identified during the four sampling seasons. Amphidinium carterae with an average of 11. 22% and A. operculatum with an average of 10. 77% of the total abundance of epiphytic dinoflagellates were the dominant species, and Gambierdiscus australes showed an average of 6. 48%. Based on the PCA, the abundance of certain species was found to be influenced by different environmental factors. The PCA revealed that NO2, NO3 and SiO4 values had the greatest impact at sites with high abundances of A. operculatum, Prorocentrum concavum, P. emarginatum, P. rhathymum and G. balechii. Furthermore, PO4 concentration had the greatest impact at the sites with high abundances of A. carterae, P. lima, Ostreopsis lenticularis, O. heptagona, G. balechii, G. toxicus, G. australes and Coolia monotis. The results obtained highlighted a significant impact of dissolved oxygen, pH, salinity, temperature and nutrients on the epiphytic dinoflagellate species abundances in the study area.

We studied the abundance, biomass and diet of Platevindex aff. tigrinus in the Hara Biosphere Reserve in the Persian Gulf. The seasonal sampling (two seasons) was conducted in winter 2018 and summer 2019. Samples were collected from six sites in Qeshm Island and Bandar Khamir. To determine the effect of environmental parameters on distribution of the species, temperature, salinity, pH, sediment grain size, total nitrogen and organic carbon were measured at each site. The results showed that the abundance of P. tigrinus was significantly higher in the winter compare to summer season. However, there was no significant difference in the biomass of the species between seasons. The PCA results showed that salinity, temperature and sediment grain size contributed to the separation of between seasons. The pH and total nitrogen followed the similar pattern in different sites and seasons. Although, temperature, salinity, sediment grain size, and organic carbon showed difference between seasons. The results showed that salinity and temperature were two important parameters in the distribution of the species during both seasons. The species was mainly feeding on the microphytobenthos during winter and on the sediment organic matter during summer.

The current study aimed to determine the isotopic composition of different food sources and their contribution to the diet of Parasesarma persicum inhibiting a mangrove ecosystem in the Persian Gulf. The potential food sources, i. e., Avicennia marina green and yellow leaves, Particulate Organic Matter (POM), Microphytobenthos (MPB), and Sediment Organic Matter (SOM) were collected for stable isotope analysis. The most 13 C-depleted values were observed for mangroves with mean δ 13 C values of-28. 31‰ and-28. 05‰ for green and yellow leaves, respectively. The mean δ 15 N values of mangrove leaves were 3. 79‰ and 5. 08‰ for green and yellow leaves, respectively. The crab P. persicum had an average value of carbon and nitrogen isotopes of-19. 48‰ , and 4. 18, respectively. The results showed that the A. marina yellow leaves (28. 1%) and SOM (13. 3%) had the highest and lowest contribution to the diet of P. persicum in the mangrove ecosystem, respectively. The results emphasize the role of mangroves in supporting estuarine food webs. This also further confirms the ecological role of sesarmid crabs as ecosystem engineers in mangrove ecosystems.

Aims: The aim of the current study was to determine the role of Avicennia marina’ s primary productions as well as other food sources in the diet of Thryssa setirostris in Hara bioshphere reserve mangrove ecosystem using stable isotopes of carbon (δ 13C) and nitrogen (δ 15N). Materials & Methods: Primary food sources including fresh and senescent leaves of Avicennia marina, microphytobenthos, particulate organic matter, and sediment organic matter were collected for further stable isotope analysis. For this purpose, fishes were collected and the muscle tissue (boneless and skinned, 5g) was removed from the dorsum of fish. Findings: Significant differences were found between carbon and nitrogen isotopes of different food sources (p<0. 05). Although, this was not significant for green and senescent leaves (p>0. 05). The average values of carbon and nitrogen isotopic ratios of T. setirostris were 15. 93 and 13. 01‰ , respectively. The SIMMR model showed that the contribution of fresh and senescent leaves in the diet of T. setirostris was 10 and 15%, respectively. Conclusion: The results of the present study depicted that the role of primary production of mangrove plants in the arid climate of the Persian Gulf is limited in feeding of T. setirostris or the organisms that this fish feed them.